Guide vane wheel of a turbomachine

Abstract

A guide vane wheel of a turbomachine, has a plurality of guide vanes, forming a blade row extending radially inward in a flow path of the turbomachine, and two borescope accesses. The guide vanes form two segments each with a plurality of guide vanes circumferentially spaced apart, with the two segments having the same, constant cascade pitch and the two segments spaced such that the respective outermost guide vane adjacent to the respective other segment has an enlarged spacing in the circumferential direction from the adjacent guide vane of the other segment equal to 1.3 to 1.7 times the cascade pitch, the sum of the increased spacings being equal to 3 times the cascade pitch. The increased distance between the respective two adjacent outermost guide vanes of the two segments creates an enlarged vane passage between these guide vanes where the borescope accesses are formed.

The invention claimed is: 
     
       1. A guide vane wheel of a turbomachine, comprising:
 a plurality of guide vanes which form a vane rower and are configured to extend radially inward in a flow path of the turbomachine, and 
 two borescope accesses, each formed between two of the vanes, 
 the plurality of guide vanes forming two segments, each with a plurality of the guide vanes, which are spaced apart from one another in a circumferential direction, 
 the two segments having a same constant cascade pitch, 
 the two segments being spaced apart such that a respective outermost one of the guide vanes of one of the two segments adjoining the other of the two segments is at an increased distance from an adjacent one of the guide vanes of the other of the two segments in the circumferential direction which is equal to 1.3 to 1.7 times the cascade pitch, the sum of the increased distances being equal to 3 times the cascade pitch, 
 the increased distance between the respective two adjacent outermost guide vanes of the two segments each providing an enlarged vane passage between two adjacent outermost guide vanes, and the two borescope accesses being formed respectively in areas of the enlarged vane passages. 
 
     
     
       2. The guide vane wheel as claimed in  claim 1 , wherein the two segments are spaced apart such that the respective outermost guide vane adjoining the respective other segment is at an increased distance from the adjacent guide vane of the other segment in the circumferential direction which is equal to 1.5 times the cascade pitch. 
     
     
       3. The guide vane wheel as claimed in  claim 1 , wherein the guide vanes of one of the two segments have a same vane profile. 
     
     
       4. The guide vane wheel as claimed in  claim 3 , wherein the guide vanes of one of the two segments has the same vane profile as the guide vanes of the other of the two segments. 
     
     
       5. The guide vane wheel as claimed in  claim 1 , wherein the two segments each have a same number of guide vanes or the number of guide vanes of the two segments differs by only one guide vane. 
     
     
       6. The guide vane wheel as claimed in  claim 1 , wherein the two segments have a different number of guide vanes, the number of guide vanes differing by at least two. 
     
     
       7. The guide vane wheel as claimed in  claim 1 , wherein the two borescope accesses are arranged in a rim surface of the guide vane wheel with respect to the respective adjacent outermost guide vanes of the two segments such that a minimum distance to the respective adjacent outermost guide vane is the same. 
     
     
       8. The guide vane wheel as claimed in  claim 1 , wherein the two borescope accesses are formed in an axially front area of the respective enlarged vane passage. 
     
     
       9. The guide vane wheel as claimed in  claim 1 , wherein an axially foremost point of the two borescope accesses adjoins a peripheral line which connects leading edges of the guide vanes of the guide vane wheel. 
     
     
       10. The guide vane wheel as claimed in  claim 1 , wherein the two borescope accesses are configured as openings in the guide vane wheel which are circular or elliptical in cross-section and run radially. 
     
     
       11. The guide vane wheel as claimed in  claim 1 , wherein the two borescope accesses each have a diameter in a range between 5 mm and 8 mm. 
     
     
       12. A gas turbine engine comprising:
 an engine core which comprises a turbines, a compressor having the guide vane wheel as claimed in  claim 1 , and a turbine shaft which is configured as a hollow shaft and connects the turbine to the compressor; 
 a fan, which is positioned upstream of the engine core, wherein the fan comprises a plurality of fan blades; and 
 a gear box that receives an input from the turbine shaft and outputs drive for the fan to drive the fan at a lower rotational speed than the turbine shaft.